Research Document - 2002/099

Observations on the witch flounder population in NAFO Subdivision 3Ps from the commercial fishery and research vessel survey data

By W.R. Bowering and D.J. Power

Abstract

Landings from this stock over the last 20 years have fluctuated between 300t and 1000 t annually. From 1986-93 landings were relatively stable averaging around 1000 t annually. During the past five years landings averaged just over 500t but were as low as 250t in 1996. The main directed fishery is prosecuted by offshore otter trawlers complemented by a nearshore Danish seine fishery. However, in recent years it appears to be a mixed American plaice and witch flounder fishery by otter trawlers. During 2000-2002 the American plaice by-catch rates in the otter trawl directed witch flounder fishery ranged from 93-143% compared to less than 5% by Danish seiners. Although survey stock size indices since 1983 have been highly variable, the survey biomass index during recent years suggests that the biomass is on average about 75% of the 1983-90 average when catches were around 800t. The age and size structure observed in this stock since the early 1980s also appear to have remained stable with little change in growth pattern. Geographic distribution has not changed appreciably since 1983 except during the early to mid 1990's when fish disappeared from the 51-100 fath. depth zone coincident with extremely cold sea bottom water temperatures. In recent years the distribution appears to be returning to a more normal pattern. No measurable change in recruitment has been observed over the past 20 years.

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